A fast autofocus sharpness function of microvision system based on the Robert function and Gauss fitting

For the microvision system, a new autofocus evaluation function based on the Robert function is proposed by increasing the threshold value. Compared with the traditional evaluation function, the new focus function reduces the local extreme value and increases the steepness of the focusing curve. According to the characteristics of the focusing evaluation function, the focus curve can be divided into two stages: the gentle area and the steep area. In the gentle area, there will be set a large step‐length to realize the fast search. In the steep area, the data will be fitted by Gauss method, and on the basis of the fitting results, the motor of microvision system was directly driven to achieve the focal plane and this method has been improved in real‐time and accuracy.     

Region sampling for robust and rapid autofocus in microscope

This paper proposes a region sampling based autofocus method for rapid and robust autofocus in microscope. Image content and region size are considered in region sampling criteria. An intelligent search algorithm which employs quartering hill climbing search and golden section search is developed, in which rule‐based evaluation of sampled focusing regions is applied. Experimental results demonstrate that the proposed method can significantly improve the performance of image‐based autofocus. Microsc. Res. Tech. 78:382–390, 2015. © 2015 Wiley Periodicals, Inc.     

Information content analysis in automated microscopy imaging using an adaptive autofocus algorithm for multimodal functions

We present a new algorithm to analyse information content in images acquired using automated fluorescence microscopy. The algorithm belongs to the group of autofocusing methods, but differs from its predecessors in that it can handle thick specimens and operate also in confocal mode. It measures the information content in images using a ‘content function’, which is essentially the same concept as a focus function. Unlike previously presented algorithms, this algorithm tries to find all significant axial positions in cases where the content function applied to real data is not unimodal, which is often the case. This requirement precludes using algorithms that rely on unimodality. Moreover, choosing a content function requires careful consideration, because some functions suppress local maxima. First, we test 19 content functions and evaluate their ability to show local maxima clearly. The results show that only six content functions succeed. To save time, the acquisition procedure needs to vary the step size adaptively, because a wide range of possible axial positions has to be passed so as not to miss a local maximum. The algorithm therefore has to assess the steepness of the content function online so that it can decide to use a bigger or smaller step size to acquire the next image. Therefore, the algorithm needs to know about typical behaviour of content functions. We show that for normalized variance, one of the most promising content functions, this knowledge can be obtained after normalizing with respect to the theoretical maximum of this function, and using hierarchical clustering. The resulting algorithm is more reliable and efficient than a simple procedure with constant steps.     

Doubled haploid production in advanced back cross generations and molecular cytogenetic characterization of rye chromatin in triticale × wheat derived doubled haploid lines

The rye genome has shown potential for improvement of bread wheat, where wheat-rye substitutions and translocations have been and are frequently used in resistance breeding. Crosses belongs to different generations viz., BC₁F₁, BC₁F₂, BC₁F₃, BC₁F₄ and BC₂F₃ of triticale × wheat derived were used for different haploid induction parameters using Gogon grass (Imperata cylindrica) as a pollen source. The percentage of pseudo seed formation ranged from 34.55% for BC₁F₂ to 63.77 for BC₁F₁ crosses, the haploid embryo formation ranges from 9.43% for BC₁F₁ to 30.2% for BC₁F₂, the haploid plant generation ranges from 19.36% for BC₁F₂ to 63.25% for BC₁F₁. Four doubled haploids were developed from ITSN 105/58 × VL 802 × VL 802 of BC₂F₃ underwent molecular cytogenetic analyses using the probes, viz., rye genomic rDNA, pSc 119 and pAs1. FISH and GISH analysis revealed an IBL.1RS translocation and substitution of 5R chromosome instead of the 5D chromosomes in these doubled haploids.     

基于迪恩涡流的流式三维聚焦芯片设计和仿真

根据迪恩涡流理论,设计了一个利用平面微加工工艺可以制作的流式三维聚焦芯片,并用FLUENT进行了仿真分析。研究了在弯管结构中,迪恩涡流的变化过程,以及样品被聚焦的过程。分析了不同的样品流速、鞘液流速对聚焦效果的影响。仿真结果验证了流式三维聚焦芯片的功能,并为三维聚焦系统控制提供了依据。     

图像测量中自动调焦函数的实验研究与分析

给出了几种常用图像测量中自动调焦算法的对比分析,并分别在不同照明方式和不同背景条件下对主要的调焦函数特性参数进行测试,得到了调焦函数的实用性能的客观评价.实验结果表明:在透射照明条件下,灰度梯度类调焦函数特性均较好.其中Variance函数以及灰度变化率和函数具有较大的调焦范围,且近似为线性变化,但是灵敏度较低,因此适于大范围粗调焦;Laplacian函数和Tenengrad函数灵敏度高,稳定性好,但调焦范围小,因此适合于小范围精确调焦.在反射照明条件下,只有Tenengrad函数和Brenner函数仍然保持单峰性,但灵敏度明显下降.当存在较复杂背景时,调焦函数普遍失效.因此在实际测试中,应当优先选择透射光照明,尽可能少用反射照明,而且应尽可能避免背景的干扰.     

基于灰关联分析的有向图法评价陶瓷材料的磨削加工性

提出一种新的陶瓷材料磨削加工性评价方法——灰关联分析的有向图法。该方法首先应用灰关联分析方法确定影响陶瓷材料磨削加工性的各种性能因素间的相关关系。在此基础上结合有向图法进行陶瓷材料磨削加工性的综合评价。以SiC、Al2O3、ZrO2和Si3N4四种陶瓷材料为例。应用该方法进行评价。评价结果能够准确地反映各种陶瓷材料的磨削加工性。     

Topographical analysis in the SEM using an automatic focusing technique

A novel technique for automated topographical analysis in the SEM has been investigated. It utilizes a 16-bit minicomputer arranged to act as an automatic focusing unit. The computer is coupled to the objective lens of the microscope, by means of a digital to analogue converter, and may regulate the excitation of the lens under program control. Further digital-to-analogue converters allow the computer to act as a programmable scan generator by applying ramp waveforms to the scan amplifiers, permitting the beam to be swept over a small sub-region of the field of interest. The video signal is sampled and applied to an analogue-to-digital converter; the resultant binary numbers are stored in computer memory as an array of values representing relative image intensities within a subregion. A differencing algorithm applied to the collected data allows the level of objective lens excitation to be found at which the sharpness of the image is optimized, and the excitation may be related to the working distance for that subregion through a previous calibration experiment. The sensitivity of the method for detecting small height changes is theoretically of the order of 1 μm.     

Flow cytometric analysis of the functional ability of neutrophils from patients with autoimmune neutropenia

Flow cytometry has been used to evaluate the functional ability of neutrophils and the expression of IgG Fc receptors (FcRII and FcRIII) in autoimmune neutropenia. Quantification of the neutrophil oxidative burst was made by assaying the production of 2′7′-dichlorofluorescein (DCF) from non-fluorescent 2′7′-dichlorofluorescin trapped within the cell, by flow cytometric analysis of cellular fluorescence. In the present study the DCF assay was used to examine the response of neutrophils to stimulation by opsonized and non-opsonized Staphylococcus aureus. In addition, the rate of uptake of S. aureus labelled with the red nuclear dye propidium iodide was determined. The presence of surface-bound immunoglobulin, which may affect the phagocytic capacity of the neutrophil, was also measured. No correlation between the neutrophil count and level of membrane-bound IgG or the rate of bacterial uptake was found. The studies were performed on twenty patients with autoimmune neutropenia, twelve with other autoimmune disorders and fourteen normal controls. The rate of uptake of bacteria was considered in relation to the expression of FcRII and FcRIII. Good correlation was found with the level of expression of FcRII, the major receptor for neutrophil activation, and the rate of uptake of bacteria (r = 0.64).     

A study on formulation of objective functions for determining material models

Optimisation techniques have been developed and used to determine material constants arising in unified creep/viscoplastic constitutive equations based on experimental data. Objective functions (OF) have been formulated as pointers to the quality of fit between the equations and experimental data and a set of criteria is presented to assess the suitability of the objective functions. Convergence features of two existing objective functions are analysed. The problems of using these objective functions are studied. To overcome difficulties arising in the existence of different scales of individual sub-objectives, a novel error definition is introduced, which has a natural unitless form and can provide a measure for “true” error. A novel weighting technique is introduced, which can also be chosen automatically to compensate the loss of credits in individual data points and curves. Using these techniques, a novel objective function is formulated, which meets the set criteria. The objective function, together with an evolutionary programming (EP) solver, are employed to determine material constants in three sets of unified constitutive equations which are formulated to match experimental data. The convergent features of the objective functions are compared and analysed.